Pinal County Sheriff Mark Lamb filed paperwork to run for U.S. Senate in Arizona, chasing the seat currently held by Democrat-turned-independent Sen. Kyrsten Sinema. Lamb, who totes a cowboy hat for public appearances, is a staunch conservative heavily aligned with former President Donald Trump, who has promoted a variety of conspiracy theories. He’s made regular appearances on Fox News to spew anti-vaccine talking points, argue for U.S. military intervention against Mexican drug cartels, and claim falsely that the 2020 election was stolen from Trump—before backtracking and saying he’d seen no evidence of voter fraud during the 2020 election. Lamb is the first major Republican candidate to join the race, but he’s expected to be joined by Kari Lake, who ran an unsuccessful 2022 Arizona gubernatorial campaign and floated entering the field in February.